venkataravi Post subject: Relationship between Resolution Bandwidth
and Recived signal Posted: Mon Sep 25, 2006 4:04 am Captain
Joined: Thu Jul 27, 2006 7:36 am Posts: 11 Location: Bangalore
--India Hi, What is the relationship between Resolution Bandwidth
and Received signal strength. With Regards Y.V.Ravi
Top IR Post subject: Posted: Mon Sep 25, 2006 1:25
pm Site Admin Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373 Location: Germany There is no relationship as the
RSSI deals with amplitude and the Resolution BW deals with frequency
_________________ Best regards, - IR Top
frmunder Post subject: Posted: Mon Sep 25, 2006 6:10 pm
Lieutenant Joined: Mon Sep 25, 2006 5:52 pm Posts:
2 As IR stated, there is not a direct relationship; but having a
large resolution bandwidth can make the noise power swamp a low level
signal. Noise power in a 1hz bandwidth is -174dBm. Increase
your bandwidth, and your noise grows by 10*log(RBW). So if your
resolution bandwidth is 10MHz, your noise power is -174dBm+10*log(10,000,000)=-107dBm.
If your signal is smaller than this level, it will be unrecognizable.
(For different modulation formats, you also need to add more power
to demodulate, i.e. C/N) To be able to "see" this signal, you
must decrease your bandwidth (as long as your signal can be processed
in the decreased bandwidth). Top IR Post subject:
Posted: Tue Sep 26, 2006 4:14 pm Site Admin Joined:
Mon Jun 27, 2005 2:02 pm Posts: 373 Location: Germany That
is true, but if you want to see the whole picture then you shouldn't
forget the tempearture contribution to the noise power: Pn=KTB
Where: K - Boltzmann's contasnt 1.38*10e-23 J/Kelvin T
- Relative temperature in Kelvin B - The bandwidth In logarithmic
terms, this formula becomes: Pn=-174dBm+10 log (T/To) + 10 log
BW So any temperature above To (290 Kelvin degrees=17 deg C)
will also increase the noise power, and according to the explanation
given above will limit the strength of the received signal.
So in conclusion RSSI is not related just to the BW, but also to surrounding
temperature... _________________ Best regards, - IR
Posted 11/12/2012
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